Table 1. Identification of 70 metabolites from the control and inoculated leaves and the determination of 16 significantly regulated metabolites associated with P. medicaginis infection.

No.	Compound	RT (min)	Characteristic fragment	Similarity	Inoculated group	Control group	p	VIP
1	Glycineab	10.452	102	90	0.025±0.001	0.035±0.002	0.001	1.199
2	Leucineab	14.581	158	95	0.270±0.016	0.362±0.020	0.001	1.214
3	Isoleucineab	15.124	158	92	0.475±0.030	0.768±0.050	0.001	1.426
4	Tyrosineab	27.909	218	96	0.119±0.011	0.228±0.013	0.001	1.577
5	Methionineab	20.166	176	94	0.018±0.005	0.066±0.006	0.001	1.532
6	5-oxoprolineab	20.233	156	95	0.161±0.011	0.121±0.006	0.001	1.146
7	Lysineab	23.843	156	96	0.070±0.004	0.093±0.006	0.001	1.088
8	GABAab	15.201	102	90	0.149±0.016	0.398±0.055	0.001	1.204
9	2-pyrrolidinonea	11.037	142	92	0.029±0.003	0.050±0.002	0.001	1.592
10	Myoinositola	28.399	217	85	0.155±0.016	0.263±0.018	0.001	1.258
		29.109	217	80
11	Inositol 1,3,4,5,6-pentakisphosphatea	30.537	554	85	0.197±0.016	0.380±0.047	0.001	1.142
12	Sucrosea	37.348	361	94	1.919±0.197	3.285±0.252	0.001	1.285
13	Malatea	19.653	233	91	1.585±0.058	0.940±0.082	0.001	1.556
14	Malonic acida	12.828	233	95	0.117±0.014	0.381±0.041	0.001	1.549
15	Palmitic acidab	29.374	313	95	0.530±0.023	0.339±0.022	0.001	1.442
16	Stearic acidab	32.325	341	99	0.537±0.028	0.327±0.030	0.001	1.321
17	Acetic acid, hydroxy-a	9.232	205	92	0.014±0.000	0.012±0.000	0.001	0.901
18	Pyruvic acid a	9.601	217	93	0.014±0.001	0.011±0.001	0.001	0.95
19	Alanineab	10.025	116	93	0.276±0.013	0.297±0.017	0.163	0.762
20	Ethanedioic acida	10.867	190	94	0.016±0.001	0.018±0.001	0.004	0.834
21	α-Aminobutyric acida	11.949	130	88	0.022±0.002	0.022±0.002	0.907	0.776
22	Ureaa	12.250	261	86	0.034±0.002	0.028±0.002	0.038	0.989
23	beta-Alaninea	12.382	102	86	0.127±0.013	0.224±0.030	0.001	0.914
24	Valineab	13.174	144	89	1.094±0.088	1.057±0.083	0.408	0.820
25	Benzoic acida	13.792	179	80	0.081±0.009	0.120±0.010	0.001	0.986
26	Phosphatea	14.658	299	89	0.144±0.018	0.111±0.010	0.024	0.817
27	Glycerola	14.724	205	93	0.327±0.022	0.313±0.014	0.522	0.768
28	Succinatea	15.495	247	85	0.995±0.124	0.888±0.060	0.108	0.772
29	Glyceric acida	16.068	189	92	0.057±0.003	0.061±0.003	0.069	0.756
30	Fumaratea	16.270	245	83	0.020±0.001	0.022±0.001	0.086	0.735
31	Pipecolic acida	16.691	156	91	0.053±0.009	0.039±0.002	0.076	0.884
32	Serineab	16.805	204	91	1.106±0.066	1.122±0.065	0.747	0.723
33	Threonineab	17.420	218	95	0.670±0.049	0.670±0.047	1	0.799
34	2-Piperidone, amino-a	18.833	128	80	0.045±0.004	0.051±0.004	0.004	0.827
35	2,2-hydroxymalonate a	19.028	308	95	0.058±0.003	0.072±0.003	0.001	0.801
36	Aspartic acidab	20.256	232	94	0.737±0.130	0.487±0.022	0.022	0.906
37	Threonic acida	21.248	292	95	0.147±0.008	0.169±0.006	0.001	0.946
38	Threo-2-pentulosea	21.703	306	80	1.575±0.098	1.369±0.073	0.03	0.864
39	Ornithineab	22.122	142	91	0.260±0.032	0.297±0.027	0.112	0.801
40	Glutamic acidab	22.235	246	94	0.368±0.017	0.360±0.020	0.742	0.517
41	Phenylalanineab	22.335	192	94	0.792±0.070	0.917±0.074	0.018	0.886
42	Arabitola	22.938	147	80	0.108±0.005	0.119±0.004	0.05	0.812
43	Asparagineab	23.308	231	95	4.276±0.407	4.110±0.323	0.467	0.799
44	Arabinosea	23.586	217	90	0.142±0.007	0.126±0.003	0.004	0.983
45	α-Aminoadipic acida	24.027	260	89	0.052±0.004	0.042±0.003	0.001	0.885
46	Phosphoric acid, 2,3- hydroxypropyl estera	25.049	357	84	0.063±0.005	0.071±0.004	0.147	0.827
47	2-keto-1-guconic acida	25.193	292	92	0.111±0.005	0.114±0.004	0.526	0.679
48	Fructofuranosea	25.906	217	85	0.294±0.035	0.390±0.054	0.033	0.796
49	Citratea	26.062	273	94	0.436±0.030	0.515±0.031	0.05	0.811
50	Pinitola	26.412	217	90	8.838±0.361	8.151±0.154	0.017	0.839
51	Adeninea	26.701	264	92	0.077±0.005	0.078±0.004	0.702	0.619
52	Fructosea	27.098	217	93	0.524±0.057	0.710±0.070	0.004	0.871
53	Sorbosea	27.279	217	89	0.628±0.070	0.899±0.100	0.001	0.895
54	Galactopyranosidea	27.506	204	88	1.529±0.106	2.139±0.054	0.002	0.896
55	Galactosea	27.542	319	86	0.940±0.120	0.946±0.067	0.001	0.652
		27.765	319	90
56	Histidineab	27.627	254	84	0.206±0.027	0.262±0.023	0.005	0.874
57	Ethyl-glucopyranosidea	28.138	204	84	0.404±0.071	0.497±0.056	0.003	0.725
58	Glucosea	28.844	204	93	0.180±0.017	0.291±0.045	0.005	0.881
		31.282	319	87
		34.968	204	91
59	Gluconic acida	29.110	333	80	0.106±0.005	0.132±0.004	0.001	0.925
60	Tryptophanab	32.253	202	93	0.324±0.029	0.343±0.023	0.223	0.763
61	Lactulosea	33.610	204	82	0.047±0.002	0.049±0.002	0.472	0.812
62	Glyceryl-glycosidea	33.813	204	90	0.175±0.012	0.172±0.004	0.748	0.618
63	Glucuronic acida	34.502	204	80	0.131±0.004	0.124±0.004	0.118	0.834
64	Uridinea	35.220	217	90	0.189±0.008	0.164±0.007	0.001	0.829
65	2-Monopalimitoylglycerola	36.077	129	88	0.043±0.001	0.041±0.002	0.254	0.719
66	Monopalmitina	36.399	371	81	0.690±0.062	0.951±0.053	0.001	0.968
67	Turanosea	36.585	361	82	0.074±0.003	0.082±0.003	0.035	0.917
68	2-Monostearina	37.922	129	80	0.077±0.004	0.077±0.003	0.817	0.578
69	Monostearina	38.317	399	86	0.163±0.006	0.188±0.007	0.003	0.915
70	Gentiobiosea	39.690	204	83	0.035±0.002	0.039±0.002	0.063	0.775

RT = retention time of compound.

^a Identified by NIST data base.

^b Identified by our in-house mass spectra library.

Data from inoculated and control groups was the average of the sum of the normalised data of the compound at each time point, which presented as Mean±SE (n = 3). The data were evaluated by a two-way analysis of variance, through which the p value was calculated. The data were determined at 2, 4, 6, 8, 12, 16, 20, 24, 26 and 28 dpi, dpi (day post inoculation). The variable importance values (VIP) were obtained through OPLS-DA analyses.